1Listen to the audio lecture while viewing these slides1Psychology 372Physiological PsychologySteven E. Meier, Ph.D.The CerebellumLittle Brain2Psyc 372 – Physiological PsychologyOverview• Is located behind the Medulla and Pons• Contains only 10% of the Brain’s volume• Contains more that 50% of the brain’s neurons• Appears similar to the cortex• Also has two hemispheres• Is co nnected to the Pons by three bundles of axons called the Cerebellar Peduncles.• Superior (Brachium Conjunctivum)• Middle (Brachium Pontis)• Inferior (Restiform Body)3Psyc 372 – Physiological PsychologyFunction Overview• Basically evaluates and adjusts motor movement while it is in progress. • Does a lot of integration and evaluation of incoming information.• Is very important for balance and motor learning4Psyc 372 – Physiological PsychologyHas Three Distinct Regions• Cerebellar cortex.•Is the outer covering• Is composed mostly of Gray Matter • Internal White Matter • Are Myelinated Axons/Fiber Tracts• Three pairs of Deep Nuclei•Fastigal•Interposed•Globo se•Emboliform• Dentate• Nuclei receive information from the cerebellar cortex• Nuclei send informatio n to the cerebellumand to other brain structures.5Psyc 372 – Physiological PsychologyThree Major Tracts of NeuronsConnect to the Brain Stem• inferior Cerebellar Peduncle• Middle Cerebellar Peduncle• Superior Cerebellar Peduncle• Has the most connections• Most input begins in deep nuclei6Psyc 372 – Physiological PsychologyAnatomically• Cerebellum surface has many parallel convolutions called Folia (leaves) that run from side to side • Has three distinct lobes separated by two fissures27Psyc 372 – Physiological PsychologyPosteriolateral fissure • Separates the body of the cerebellum from the Flocculonodular lobe• Is the primary fissure in the body of the cerebellum • Separates the anterior lobe from the posterior lobe• Lobes are important functionally8Psyc 372 – Physiological PsychologyFissures• Define a ridge in the midline called the vermis• On each side of the vermis are the cerebellar hemispheres• Hemispheres are divided into intermediate and lateral regions.• Each is important for specific motor functions 9Psyc 372 – Physiological PsychologyFlocculonodular Lobe(Vestibulocerebellum)• Is most primitive• Gets information from vestibular areas of the brain.• Semicircular canals• Otoliths• Is extremely important for balance and eye movements10Psyc 372 – Physiological PsychologyDamage• Problems with eye movements during head rotations• Problems with limbs and body structures during standing or walking• Have problems maintaining balance• Patients separate legs but the move their legs irregularly and often fall• Can move arms and legs accurately when lying down or when their head is supported11Psyc 372 – Physiological PsychologyVermis • Gets information from visual auditory and vestibular areas.• Also gets information from somatic sensory areas as well.• Helps control the proximal muscles of the body and limbs.• Generally governs posture, locomotion, and gaze.12Psyc 372 – Physiological PsychologyIntermediate Zone• Gets somatosensory information from limbs• Helps control distal muscles of the limbs and fingers313Psyc 372 – Physiological PsychologyVermis and Intermediate Zones(Spinocerebellum) • Receives information from the spinal cord.• Also gets information from ventral and dorsal spinocerebellar tracts.• Receives information from the leg muscles and joints• Sends information to structures that develop into the rubrospinal and corticospinal tracts.14Psyc 372 – Physiological PsychologyFunction• Influences limb muscles and muscles in the body• Don’t get limb deceleration - so you get overshoot of the system• Is especially important for rhythmic activity during locomotion• Also contains inverted somatotopic maps that are inverted• E.g., head is at the bottom in the vermis15Psyc 372 – Physiological PsychologyCerebrocerebellum • Are lateral parts of the hemispheres• Only receives information from the cortex• Is involved with planning and mental rehearsal of complex motor actions and • Conscious assessment of movement errors.• Has a very important role in perceptual and cognitive functioning16Psyc 372 – Physiological PsychologyDamage• Disrupts motor planning and prolongs reaction times• Have to plan out every movement before doing it.17Psyc 372 – Physiological PsychologyExample, tapping tests on Halstad Reitan• Rhythm is irregular and the motions vary in duration and force. • Medial cerebellar lesions interfere only with accurate execution of the response• Lateral cerebellar lesions interfered with the timing of the events• Timing was also disrupted in other cognitive tasks as well18Psyc 372 – Physiological PsychologyQuestion• Is one tone longer than another?• Is the speed of an object faster than another?• Dentate also is important for tasks requiring complex spatial and temporal judgments• Is essential for conducting complex motor movements419Psyc 372 – Physiological PsychologySome Disorders• Lots of disorders• Diag no sis is o ften done sym ptomatically•Examples• Hypotonia• Knee jerk• You flex but the leg does not come back smoothly• Instead ossicilates several times•Ataxia• Lack of coordination• Also get a delay in initiating responses with t he affected limb• Also get errors in the range and regularityof movement20Psyc 372 – Physiological Psychologye.g., Hand Alternation Task• Have fingers hit alternate palm of the hand• Get tremor when you are trying to stop the movement • Problem occurs when antagonistic muscles are trying to stop the movement.21Psyc 372 – Physiological PsychologyOverall Damage to Cerebellum• Generally, results in jerky, exaggerated, erratic motor movements.• Movements are also poorly